In the long-term evolution (LTE) system, system information may be divided into main information block (MIB), system information block 1 (SIB1) and ordinary system information (SI).
Wherein the MIB is transmitted in a broadcasting channel with a transmitting cycle of 40 milliseconds, and the MIB is repeatedly transmitted in sub-frame #0 of each wireless frame within its transmitting cycle. SIB1 is transmitted in a downlink shared channel with a scheduling cycle of 80 milliseconds, and SIB1 is repeatedly transmitted in sub-frame #5 (sub-frame number starts from 0) of a wireless frame satisfying SFN % 2=0 (wherein SFN is the system frame name) within its scheduling cycle; and other system parameters are included in other system information blocks (SIB). In respect of other SIBs, there are already SIBs from SIB2 to SIB8 in the present LTE system. The contents of system parameters comprise service cell information, cell reselection information and adjacent cell information of intra-frequency, inter-frequency and other radio access technologies (RAT) etc.
The above SIBs are mapped into different SIs to realize scheduling, that is, the SIBs are defined according to their contents, wherein SI serves as a scheduling unit, the scheduling information of these SIs are included in SIB1, and the scheduling information specifically comprises a transmitting window w, a scheduling cycle n and so on. The order that the SI appears in the scheduling information of SIB1 is called as scheduling order n, the transmitting windows of all SIs are the same, but the scheduling cycles may be different. The transmitting window of the SI is a limited time range, within which the SIBs mapped into the same SI are repeatedly transmitted, but it is not determined in which sub-frame the transmission is conducted, that is, a terminal needs to try to receive and decode the SI in each sub-frame within the transmitting window. In the LTE system, to simplify the scheduling process, the relation between the scheduling cycles N of all SIs is in general that one is simply multiple of another, and they all have even number of frames. For example, the scheduling cycle N may be 8 frames, 16 frames and so on, which makes a certain SFN to become a common multiple of some SIs, i.e. satisfying SFN % Ni=0. To facilitate description, the above SI is called SI group on the SFN in the following description.
The scheduling rule of SI is described as follows: supposing that the size of the transmitting window is w sub-frames, the scheduling cycle of a certain SI is N and the scheduling order thereof is n, then the starting wireless frame and sub-frame of the transmitting window of the system information may be represented by the following formulae: SFN % N=COUNT+floor(w*(n−1)/10), sub-frame=(w*(n−1)) % 10, wherein COUNT is a constant and may be 0 or 8 for example. If COUNT is larger than or equal to N, then COUNT shall be modified to be COUNT % N. It can be seen that when n=1, sub-frame=0, that is, the transmitting window of SI with n=1 begins from sub-frame #0 of the wireless frame satisfying SFN % N=COUNT. For the SIs with n larger than 1, following the SI with n=1, they shall be continuously transmitted within their respective transmitting windows in sequence. For example, it is assumed that there are 7 SIBs all together, i.e. SIB2, SIB3, SIB4, SIB5, SIB6, SIB7 and SIB8, and these SIBs are mapped into 7 SIs, i.e. SI-2, SI-3, SI-4, SI-5, SI-6, SI-7 and SI-8, in a one-to-one manner and their scheduling cycles are 160 ms, 320 ms, 640 ms, 640 ms, 1280 ms, 1280 ms and 1280 ms, respectively. FIG. 1 is a schematic diagram showing the scheduling rule of each SIB above, wherein the transmitting window is 20 ms and COUNT=0. As shown in FIG. 1, the SI group on SFN=0 comprises SI-2, SI-3, SI-4, SI-5, SI-6, SI-7 and SI-8, the transmitting window of SI-2 begins from sub-frame #0 of SFN #0, and other SIs are continuously transmitted within their respective 20 ms transmitting windows in sequence. The SI group on SFN=32 comprises SI-2 and SI-3; the SI groups on SFN=16 and SFN=48 comprise SI-2; and the SI group on SFN=64 comprises SI-2, SI-3, SI-4 and SI-5.
Since the scheduling cycle of SIB1 is 80 ms and SIB1 is transmitted on fixed wireless frames and sub-frames, SIB1 is allowed to be transmitted within transmitting windows of other SI in order to facilitate the scheduling of other SI. However, it is specified in the LTE system that other SIs are not allowed to be transmitted in sub-frame #5 satisfying SFN % 2=0 in order to avoid mixing SIB1 and other SIs on the same sub-frame.
At present, the size of the transmitting window of the SI ranges among (1 ms, 2 ms, 5 ms, 10 ms, 15 ms, 20 ms, 40 ms, spare) in the LTE system, wherein when the size of the transmitting window is 1 ms, according to the present scheduling rule, a phenomena will appear that the transmissions of SIB1 and other SIs overlap with each other within the same sub-frame when the number of the scheduled SIs is larger than or equal to 6. FIG. 2 is a schematic diagram showing the phenomena that the transmissions of SIB1 and other SIs overlaps with each other within the same sub-frame. As shown in FIG. 2, the SI group on frame #0 is transmitted within successive sub-frames beginning from sub-frame #0 of wireless frame #0. Since the scheduled SI-7 is transmitted in sub-frame #5 of wireless frame #0, it conflicts with the transmission of SIB1.